Saturday, March 06, 2010

Compromises: Aperture

For the next several days we'll cover many different topics all in the theme of the compromises we make with every image.

When we chose a setting, we do so to achieve a particular effect and at the same time we give up something.

Today's topic is aperture. We use a large aperture to produce a short depth of field and a small aperture to create a large depth of field.

But what are the other effects? A large aperture like f/2.8 lets in lots of light and a small aperture like f/22 lets in very little.

Lots of light let's us use a much faster shutter speed than otherwise.

The one other thing that happens withal small aperture, say f/11 and smaller (for 35mm) is we encounter a diffraction effect, which results in a limit to the effective resolution.

Finally most lenses are sharpest in the middle of the aperture range.

So we use large, medium and smaller apertures for which ever creative effect we want with the depth of field. And at the same time we introduce other changes we may not want.
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